Ions are used in a plurality of semiconductor processes, such as implantation, amorphization, deposition and etching processes. In many embodiments, positive ions are created from a plasma and are used to perform these processes.
For example, an RF ion source may be used. This RF ion source may include an RF antenna, to which RF power is applied. The RF antenna may be disposed near a wall of the chamber, which may be made of a dielectric material. One or more gas containers may be in communication with the chamber so as to supply feed gas to the chamber of the RF ion source. The excitation of the RF antenna results in the creation of electromagnetic energy, which may excite feed gas disposed with the chamber of the RF ion source to create a plasma. Ions from this plasma may be extracted from the RF ion source using, for example, extraction electrodes, and directed toward a workpiece. These extracted ions may become implanted in the workpiece.
Pulsed electronegative plasmas are promising candidates for improving etch, deposition processes for precision material modifications and microelectronics fabrication. Negative ions can be used to reduce charge build-up on the devices and provide “charge free” ion beam processing. In addition, pulsed electronegative plasmas can have extremely high negative ion to electron density ratio and can be used as a negative ion source. When negative ions dominate in the afterglow plasma, then electron filtering at the extraction aperture is not necessary. Electron filtering is typically done in a continuous (cw) negative ion sources.
In certain embodiments, it may be beneficial to create a negative ion beam. Further, it would be advantageous if this negative ion beam can be adjusted, so that parameters, such as neutral to ion flux ratio, angle control, and uniformity, can be readily controlled.